Impaired OTUD7A-dependent Ankyrin regulation mediates neuronal dysfunction in mouse and human models of the 15q13.3 microdeletion syndrome

Brianna K. Unda, Leon Chalil, Sehyoun Yoon, Savannah Kilpatrick, Courtney Irwin, Sansi Xing, Nadeem Murtaza, Anran Cheng, Chad Brown, Alexandria Afonso, Elizabeth McCready, Gabriel M. Ronen, Jennifer Howe, Aurélie Caye-Eude, Alain Verloes, Brad W. Doble, Laurence Faivre, Antonio Vitobello, Stephen W. Scherer, Yu LuPeter Penzes, Karun K. Singh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Copy number variations (CNVs) are associated with psychiatric and neurodevelopmental disorders (NDDs), and most, including the recurrent 15q13.3 microdeletion disorder, have unknown disease mechanisms. We used a heterozygous 15q13.3 microdeletion mouse model and patient iPSC-derived neurons to reveal developmental defects in neuronal maturation and network activity. To identify the underlying molecular dysfunction, we developed a neuron-specific proximity-labeling proteomics (BioID2) pipeline, combined with patient mutations, to target the 15q13.3 CNV genetic driver OTUD7A. OTUD7A is an emerging independent NDD risk gene with no known function in the brain, but has putative deubiquitinase function. The OTUD7A protein–protein interaction network included synaptic, axonal, and cytoskeletal proteins and was enriched for ASD and epilepsy risk genes (Ank3, Ank2, SPTAN1, SPTBN1). The interactions between OTUD7A and Ankyrin-G (Ank3) and Ankyrin-B (Ank2) were disrupted by an epilepsy-associated OTUD7A L233F variant. Further investigation of Ankyrin-G in mouse and human 15q13.3 microdeletion and OTUD7AL233F/L233F models revealed protein instability, increased polyubiquitination, and decreased levels in the axon initial segment, while structured illumination microscopy identified reduced Ankyrin-G nanodomains in dendritic spines. Functional analysis of human 15q13.3 microdeletion and OTUD7AL233F/L233F models revealed shared and distinct impairments to axonal growth and intrinsic excitability. Importantly, restoring OTUD7A or Ankyrin-G expression in 15q13.3 microdeletion neurons led to a reversal of abnormalities. These data reveal a critical OTUD7A-Ankyrin pathway in neuronal development, which is impaired in the 15q13.3 microdeletion syndrome, leading to neuronal dysfunction. Furthermore, our study highlights the utility of targeting CNV genes using cell type-specific proteomics to identify shared and unexplored disease mechanisms across NDDs.

Original languageEnglish (US)
Pages (from-to)1747-1769
Number of pages23
JournalMolecular Psychiatry
Volume28
Issue number4
DOIs
StatePublished - Apr 2023

Funding

This work was supported by grants to KKS (Canadian Institutes of Health Research [CIHR], Natural Sciences and Engineering Research Council [NSERC], the Ontario Brain Institute (OBI), and The Network of European Funding for Neuroscience Research (ERA-NET Neuron) and PP (R01MH097216). We would also like to thank Dr Vann Bennett (Duke University) for his advice related to Ankyrin-G experiments and reagents. All schematics were created with BioRender.com.

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience
  • Psychiatry and Mental health

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